Steel golf shaft with a composite pivot area

ABSTRACT

A golf club shaft having an upper hollow portion with a handle end and a lower hollow portion with a head end and an intermediate flex portion therebetween. The upper portion has a lower end with a joining region extending into the flex portion. The lower portion has an upper end with a joining region extending into the flex portion. A connector in the flex portion has a central enlarged cylindrical section with a diameter extending outwardly to a diameter essentially equal to the exterior surface of the adjacent shaft portions, the connector also having an upper cylindrical section with a reduced diameter in interference contact with the interior surface at the lower end of the upper portion, the connector also having a lower cylindrical section with a reduced diameter in interference contact with the interior surface at the upper end of the lower portion of the shaft.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a steel golf shaft with acomposite pivot area and more particularly pertains to tailoring theplaying characteristics of golf clubs through an intermediate pivot areain the shaft.

[0003] 2. Description of the Prior Art

[0004] The use of golf shafts with variable playing characteristics ofvarious designs and configurations is known in the prior art. Morespecifically, golf shafts with variable characteristics of variousdesigns and configurations heretofore devised and utilized for thepurpose of tailoring the playing characteristics of golf clubs throughvarious methods and apparatus are known to consist basically offamiliar, expected, and obvious structural configurations,notwithstanding the myriad of designs encompassed by the crowded priorart which has been developed for the fulfillment of countless objectivesand requirements.

[0005] By way of example, note U.S. Pat. No. 5,439,219 to Vincent, U.S.Pat. No. 5,308,062 to Hogan and U.S. Pat. No. 5,467,984 to Veux.

[0006] While these devices fulfill their respective, particularobjectives and requirements, the aforementioned patents do not describea golf shaft with a composite or plastic pivot area that allowstailoring the playing characteristics of golf clubs through anintermediate pivot area in the shaft.

[0007] In this respect, the golf shaft with a composite pivot areaaccording to the present invention substantially departs from theconventional concepts and designs of the prior art, and in doing soprovides an apparatus primarily developed for the purpose of tailoringthe playing characteristics of golf clubs through an intermediate pivotarea in the shaft.

[0008] Therefore, it can be appreciated that there exists a continuingneed for a new and improved golf shaft with a composite pivot area whichcan be used for tailoring the playing characteristics of golf clubsthrough an intermediate pivot area in the shaft. In this regard, thepresent invention substantially fulfills this need.

SUMMARY OF THE INVENTION

[0009] In view of the foregoing disadvantages inherent in the knowntypes of golf shafts with variable playing characteristics of variousdesigns and configurations now present in the prior art, the presentinvention provides an improved golf shaft with a composite pivot area.As such, the general purpose of the present invention, which will bedescribed subsequently in greater detail, is to provide a new andimproved a golf shaft with a composite pivot area and method which hasall the advantages of the prior art and none of the disadvantages.

[0010] To attain this, the present invention essentially comprises a newand improved golf club comprising a shaft having a handle end with agrip thereon and a head end with a head thereon and an intermediate flexportion therebetween. One embodiment of the shaft is for a driver andwould include an upper hollow steel portion about 26 inches in lengthconstituting between about 55 and 65 percent, preferably 59.6 percent,of the length of the shaft. Also included in the shaft is a lower hollowsteel portion about 12.5 inches in length constituting between about 25and 33 percent, preferably 28.8 percent of the length of the shaft. Anintermediate flex portion about 9 inches in length with about 2 inchesat each end is positioned within the upper and lower portions leavingabout 5 inches therebetween constituting between 9 and 14 percent,preferably 11.6 percent, of the length of the shaft. The lower end ofthe upper portion of the shaft remote from the handle having an exteriorundercut region extending into the intermediate flex portion with theupper end of the lower portion of the shaft remote from the head havingan exteriorly undercut region extending into the intermediate flexportion. A cylindrical sleeve is formed of a plurality of layers of anoverwrap of a composite material having an upper and lower radialabutment in contact with the lower end of the upper portion of the shaftand the upper end of the lower portion of the shaft and having an upperend of a reduced diameter in contact with the undercut region of thelower end of the upper portion of the shaft and a lower end of a reduceddiameter in contact with the undercut region of the upper end of thelower portion of shaft, and with the exterior surface of the cylindricalsleeve between the upper and lower portion of the shaft forming a smoothcontinuation of the shaft through the intermediate flex portion with thesleeve forming a region of greater flexibility than the portions of theshaft thereabove and therebelow for tailoring the playingcharacteristics of the golf clubs.

[0011] There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject matter of the claims appended hereto.

[0012] In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of descriptions and should not beregarded as limiting.

[0013] As such, those skilled in the art will appreciate that theconception, upon which this disclosure is based, may readily be utilizedas a basis for the designing of other structures, methods and systemsfor calling out the several purposes of the present invention. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the present invention.

[0014] It is therefore an object of the present invention to provide anew and improved golf shaft with a composite pivot area which has all ofthe advantages of the prior art golf shafts with variable playingcharacteristics of various designs and configurations and none of thedisadvantages.

[0015] It is another object of the present invention to provide a newand improved golf shaft with a composite pivot area which may be easilyand efficiently manufactured and marketed.

[0016] It is a further object of the present invention to provide a newand improved golf shaft with a composite pivot area which is of durableand reliable constructions.

[0017] An even further object of the present invention is to provide anew and improved golf shaft with a composite pivot area which issusceptible of a low cost of manufacture with regard to both materialsand labor, and which accordingly is then susceptible of low prices ofsale to the consuming public, thereby making such golf shaft with acomposite pivot area economically available to the buying public.

[0018] Even still another object of the present invention is to providea golf shaft with a composite pivot area for tailoring the playingcharacteristics of golf clubs through an intermediate pivot area in theshaft.

[0019] Lastly, it is an object of the present invention to provide a newand improved golf club shaft having an upper hollow portion with ahandle end and a lower hollow portion with a head end and anintermediate flex portion therebetween. The upper portion has a lowerend with a joining region extending into the flex portion. The lowerportion has an upper end with a joining region extending into the flexportion. A connector is provided in the flex portion having a centralenlarged cylindrical section with a diameter extending outwardly to adiameter essentially equal to the exterior surface of the adjacent shaftportions, the connector also having an upper cylindrical section with areduced diameter in interference contact with the interior surface atthe lower end of the upper portion, the connector also having a lowercylindrical section with a reduced diameter in interference contact withthe interior surface at the upper end of the lower portion of the shaft.

[0020] These together with other objects of the invention, along withthe various features of novelty which characterize the invention, arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and the specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will be better understood and objects other thanthose set forth above will become apparent when consideration is givento the following detailed description thereof. Such description makesreference to the annexed drawings wherein:

[0022]FIG. 1 is a perspective view of the preferred embodiment of a golfclub employing a shaft with a composite pivot area constructed inaccordance with the principles of the present invention.

[0023]FIGS. 1a, 1 b, and 1 c illustrate alternate embodiments of theinvention wherein the insert is of varying lengths.

[0024]FIG. 2 is perspective showing of the shaft employed in a golf clubof FIG. 1.

[0025]FIG. 3 is an enlarged showing of the intermediate flex region ofthe golf club shaft taken at circle 3 of FIG. 2.

[0026]FIG. 4 is a cross sectional view taken along line 4 of FIG. 3.

[0027]FIG. 5 is a side elevational view taken at line 5-5 of FIG. 4.

[0028]FIG. 6 is a cross sectional view similar to FIG. 3 butillustrating an alternate embodiment of the invention.

[0029] The same reference numerals refer to the same parts through thevarious Figures.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] With reference now to the drawings, and in particular to FIG. 1thereof, the preferred embodiment of the new and improved golf shaftwith a composite pivot area embodying the principles and concepts of thepresent invention and generally designated by the reference numeral 10will be described.

[0031] The present invention, the golf shaft with a composite pivotarea, is comprised of a plurality of components. Such components intheir broadest context include a shaft with a metal upper portion and ametal lower portion and with a non-metallic flex portion therebetween.Such components are individually configured and correlated with respectto each other so as to attain the desired objective.

[0032] The primary component of the present invention is a shaft 12.Such shaft has a handle end 14 with a grip 16 thereon. It also has ahead end 18 with a head 20 formed thereon. In addition, the shaftincludes an intermediate flex portion 22 between the upper and lowerends.

[0033] In the preferred embodiment of FIG. 1, there is shown theinvention including a shaft about 44 inches in length, a normal shaftlength for a driver. Such shaft has an upper hollow steel portion 24about 26 inches in length and constitutes between about 55 and 65percent, preferably 59.6 percent, of the length of the shaft. The shaftalso has a lower hollow steel portion 26 about 12.5 inches in length andconstitutes between about 25 and 33 percent, preferably 28.8 percent, ofthe length of the shaft. The shaft also has an intermediate flex portion22 about 9 inches in length with about 2 inches at each end within theupper and lower portions. This leaves about 5 inches therebetweenconstituting between 9 and 14 percent, preferably 11.6 percent, of thelength of the shaft.

[0034] The lower end of the upper portion of the shaft remote from thehandle has an undercut or joining region 32 which extends into theintermediate flex portion. The upper end of the lower portion of theshaft remote from the head has an undercut or joining region 34extending into the intermediate flex portion.

[0035] A cylindrical sleeve 38 is formed of a plurality of layers of acomposite material. The sleeve has an upper and lower radial abutmentsurface 40, 42 in contact with the lower end of the upper portion of theshaft and the upper end of the lower portion of the shaft.

[0036] The sleeve has an upper end 44 of a reduced diameter in contactwith the undercut region of the lower end of the upper portion of theshaft. The sleeve also has a lower end 46 of a reduced diameter incontact with the undercut region of the upper end of the lower portionof shaft. The exterior surface of the cylindrical sleeve between theupper and lower portion of the shaft forms a smooth continuation of theshaft through the intermediate flex portion with the sleeve forming aregion of greater flexibility than the portions of the shaft thereaboveand therebelow. This allows for tailoring the playing characteristics ofthe golf clubs. It should be noted that the preferred embodimentillustrates the intermediate portion as having undercut ends for theaccommodation of the adjacent portions of the upper and lower portions.It should be understood, that an inverted relationship could be utilizedwith the intermediate portion being tubular of a common diameterthroughout its length and with the adjacent ends of the upper and lowerportions being of a reduced diameter thereadjacent to fit within thehollow interior of the intermediate section.

[0037] The preferred materials for the sleeve include any conventionalmatrix material for the binder and with essentially inextensible strandstherethrough as of graphite, carbon, glass, and other known materialsfor its intended purpose. The strands may be axially aligned with theshaft or at any angle, preferably up to 45 degrees to assist in varyingthe flex characteristics of the shaft. This arrangement forms a regionof greater flex than the portions of the shaft thereabove and therebelowfor tailoring the playing characteristics of the golf clubs as afunction of the materials of the components, the angle of the strands,in combination with the size and positioning of the connector and sleevewith respect to the shaft portions.

[0038] In the preferred embodiment, the connector is fabricated as acomposite hollow cylinder with a plurality of layers. Each layerincludes aligned strands of inextensible fibers such as graphite,carbon, glass or any of the conventional materials utilizedconventionally in composite materials. The strands are held in positionby a flexible polymer functioning as the matrix binder material. Suchmatrix binder material may be of any of the conventional bindermaterials normally used in composite technology. The fibers in thepreferred embodiment are aligned at any desired angle. They are shown inFIG. 5 as extending at about forty-five degrees from the axis of theshaft. They may be placed at any angle preferably lower down to zerodegrees, at an orientation parallel with the axis of the shaft. Theangular orientation will vary the flux of the connector in the one flexportion of the club.

[0039] Note is taken that the shaft above and below the connector arethe stiffest portion of the shaft. The portion of the connector betweenthe shaft is the region of greatest flex. The regions under the adjacentends of the shaft which are undercut and provided with compositematerial of a lesser thickness are of an intermediate flexibility.

[0040] The current preferred embodiment of the invention for a drivershaft utilizes a composite connector between two steel tubes. The buttsection of the steel is 26 inches in length. The tip portion of thesteel shaft is 12.5 inches in length. The hollow composite section is 9inches in length. Two inches at either end of the composite pieces slideinto the steel portions of the shaft to which they are adhesivelybonded. Thus, the total active length of the shaft is 43.5 inches. Thecomposite tube is produced via a bladder molding operation. It has awall thickness of about 0.040 inches and is composed of approximately 7layers of graphite epoxy material. The fibers are oriented at anglesthat range from 0 degrees, along the length of the shaft, to 45 degrees.The exact fiber orientation is varied from shaft to shaft depending onthe desired amount of flexibility.

[0041] In the FIG. 6 embodiment, the connector 50 is fabricated ofplastic in a hollow configuration. This embodiment has a cross-sectionof a connector similar to that of the primary embodiment describedabove. Such connector provides further cost advantages over that of theprimary embodiment.

[0042]FIGS. 1a, 1 b, and 1 c show alternate inserts where the flexportions are of varying lengths. In the FIG. 1a embodiment, theintermediate flex portion is of a length less than that of the primaryembodiment; in the embodiment of FIG. 1b, the intermediate flex portionis of a length greater than that of the primary embodiment but less thanhalf the length of the shaft.

[0043] In the embodiment of FIG. 1c, the intermediate flex portion is ofa length greater than 50 percent of the length of the shaft, preferablyabout 65 percent of the total length of the shaft. A low cost version ofthe shaft would be to use a small middle section, from between aboutfive and nine inches in length, and steel upper and lower portions. Thiswould tend to be a fairly heavy shaft when compared to an all-compositeshaft. A more expensive, and higher performance version of this shaft,would incorporate a much larger middle section composed of compositematerials, preferably graphite fibers in an epoxy matrix. The compositesection in this case could, as mentioned above, account for up to 65percent of the total length of the shaft.

[0044] It should also be understood that, although the primaryembodiment discloses the upper and lower portions of the shaft as beingof steel tubes, other metals could be utilized. The other metals thatcould be utilized include metals selected from the class of metalsincluding aluminum, titanium and other metal alloys.

[0045] The major benefit to this type of shaft would be to offer acontrolled kick point in a shaft. By varying the stiffness of thecomposite region only, shafts of significantly different performance canbe produced. The shaft should also transmit less shock and vibration toplayers hands when compared to traditional steel shafts, but may offermore feedback than an all graphite shaft. By utilizing steel in the tipportion and a composite mid section, it should be possible to produce adurable, low torque shaft, that still adds club head speed due to itslocalized flex point.

[0046] As to the manner of usage and operation of the present invention,the same should be apparent from the above description. Accordingly, nofurther discussion relating to the manner of usage and operation will beprovided.

[0047] With respect to the above description then, it is to be realizedthat the optimum dimensional relationships for the parts of theinvention, to include variations in size, materials, shape, form,function and manner of operation, assembly and use, are deemed readilyapparent and obvious to one skilled in the art, and all equivalentrelationships to those illustrated in the drawings and described in thespecification are intended to be encompassed by the present invention.

[0048] Therefore, the foregoing is considered as illustrative only ofthe principles of the invention. Further, since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and accordingly, all suitable modifications andequivalents may be resorted to, falling within the scope of theinvention.

What is claimed as being new and desired to be protected by LettersPatent of the United States is as follows:
 1. A new and improved golfclub comprising a shaft having a handle end with a grip thereon and ahead end with a head thereon and an intermediate flex portiontherebetween comprising, in combination: a shaft including an upperhollow steel portion about 26 inches in length constituting betweenabout 55 and 65 percent, preferably 59.6 percent, of the length of theshaft and a lower hollow steel portion about 12.5 inches in lengthconstituting between about 25 and 33 percent, preferably 28.8 percent ofthe length of the shaft with an intermediate flex portion about 9 inchesin length with about 2 inches at each end within the upper and lowerportions leaving about 5 inches therebetween constituting between 9 and14 percent, preferably 11.6 percent, of the length of the shaft, thelower end of the upper portion of shaft remote from the handle having anundercut region extending into the intermediate flex portion with theupper end of the lower portion of the shaft remote from the head havingan undercut region extending into the intermediate flex portion; and acylindrical sleeve formed of a plurality of layers of a compositematerial having an upper and lower radial abutment surface in contactwith the lower end of the upper portion of the shaft and the upper endof the lower portion of the shaft and having an upper end of a reduceddiameter in contact with the undercut region of the lower end of theupper portion of the shaft and a lower end of a reduced diameter incontact with the undercut region of the upper end of the lower portionof shaft, and with the exterior surface of the cylindrical sleevebetween the upper and lower portion of the shaft forming a smoothcontinuation of the shaft through the intermediate flex portion with thesleeve forming a region of greater flexibility than the portions of theshaft thereabove and therebelow for tailoring the playingcharacteristics of the golf clubs.
 2. A golf club shaft having an upperhollow portion with a handle end and a lower hollow portion with a headend and an intermediate flex portion therebetween comprising: the upperportion having a lower end with a joining region extending into the flexportion, the lower portion having an upper end with a joining regionextending into the flex portion; and a connector in the flex portionhaving a central enlarged cylindrical section with a diameter extendingoutwardly to a diameter essentially equal to the exterior surface of theadjacent shaft portions, the connector also having an upper cylindricalsection in interference contact with the lower end of the upper portion,the connector also having a lower cylindrical section in interferencecontact with the upper end of the lower portion of the shaft.
 3. Theshaft as set forth in claim 2 wherein the upper and lower portions ofthe shaft are fabricated of steel.
 4. The shaft as set forth in claim 2wherein the upper portion of the shaft constitutes between about 55 and65 percent of the length of the shaft.
 5. The shaft as set forth inclaim 2 wherein the intermediate flex portion constitutes between about9 and 14 percent of the length of the shaft.
 6. The shaft as set forthin claim 2 wherein the intermediate flex portion constitutes up to about65 percent of the total shaft length.
 7. The shaft as set forth in claim2 wherein the lower portion of the shaft constitutes between about 9 and14 percent of the length of the shaft.
 8. The shaft as set forth inclaim 2 wherein the connector is formed of a non-metallic material. 9.The shaft as set forth in claim 2 wherein the connector is formed of acomposite material with inextensible strands from between about 0degrees and 45 degrees with respect to the axis of the shaft.
 10. Theshaft as set forth in claim 2 wherein the connector is formed ofplastic.
 11. The shaft as set forth in claim 2 wherein the upper end andlower end are selected from the class of metals including aluminum,titanium and other metal alloys.